/*
 * RegistryBinder.java January 2010
 *
 * Copyright (C) 2010, Niall Gallagher <niallg@users.sf.net>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package wx.xml.simpleframework.xml.convert;

import wx.xml.simpleframework.xml.util.Cache;
import wx.xml.simpleframework.xml.util.ConcurrentCache;

/**
 * The <code>RegistryBinder</code> object is used acquire converters
 * using a binding between a type and its converter. All converters
 * instantiated are cached internally to ensure that the overhead
 * of acquiring a converter is reduced. Converters are created on
 * demand to ensure they are instantiated only if required.
 *
 * @author Niall Gallagher
 * @see wx.xml.simpleframework.xml.convert.Registry
 */
class RegistryBinder {

    /**
     * This is used to instantiate and cache the converter objects.
     */
    private final ConverterFactory factory;

    /**
     * This is used to cache bindings between types and converters.
     */
    private final Cache<Class> cache;

    /**
     * Constructor for the <code>RegistryBinder</code> object. This
     * is used to create bindings between classes and the converters
     * that should be used to serialize and deserialize the instances.
     * All converters are instantiated once and cached for reuse.
     */
    public RegistryBinder() {
        this.cache = new ConcurrentCache<Class>();
        this.factory = new ConverterFactory();
    }

    /**
     * This is used to acquire a <code>Converter</code> instance from
     * this binder. All instances are cached to reduce the overhead
     * of lookups during the serialization process. Converters are
     * lazily instantiated and so are only created if demanded.
     *
     * @param type this is the type to find the converter for
     * @return this returns the converter instance for the type
     */
    public Converter lookup(Class type) throws Exception {
        Class result = cache.fetch(type);

        if (result != null) {
            return create(result);
        }
        return null;
    }

    /**
     * This is used to acquire a <code>Converter</code> instance from
     * this binder. All instances are cached to reduce the overhead
     * of lookups during the serialization process. Converters are
     * lazily instantiated and so are only created if demanded.
     *
     * @param type this is the type to find the converter for
     * @return this returns the converter instance for the type
     */
    private Converter create(Class type) throws Exception {
        return factory.getInstance(type);
    }

    /**
     * This is used to register a binding between a type and the
     * converter used to serialize and deserialize it. During the
     * serialization process the converters are retrieved and
     * used to convert the object properties to XML.
     *
     * @param type      this is the object type to bind to a converter
     * @param converter this is the converter class to be used
     */
    public void bind(Class type, Class converter) throws Exception {
        cache.cache(type, converter);
    }
}
